1. Field of the Invention
The present invention relates to a dividing method for dividing a light emitting device wafer into individual light emitting devices, and more particularly to a dividing method for dividing a sapphire wafer.
2. Description of the Related Art
A light emitting device such as a light emitting diode (LED) having a sapphire layer and a light emitting layer formed on the front side of the sapphire layer is known (see Japanese Patent Laid-open No. Hei 10-056203, for example). This light emitting device is manufactured by dividing a sapphire wafer into a plurality of pieces along a plurality of crossing division lines, wherein the sapphire wafer is composed of a sapphire substrate and a light emitting layer formed on the front side of the sapphire substrate. As a dividing method for a light emitting device wafer such as a sapphire wafer, a dividing method using laser processing is known (see Japanese Patent Laid-open No. Hei 10-305420 and Japanese Patent No. 3408805, for example).
According to the dividing method described in Japanese Patent Laid-open No. Hei 10-305420, a pulsed laser beam is applied to the wafer to form a plurality of laser processed grooves on the front side of the wafer along the division lines, and an external force is next applied to the laser processed grooves to divide the wafer. According to the dividing method described in Japanese Patent No. 3408805, a pulsed laser beam having a transmission wavelength is applied to the wafer to form a plurality of continuous modified layers inside the wafer along the division lines, and an external force is applied to the modified layers reduced in strength to divide the wafer.